<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
      /*id选择器*/
      #p1{color:red}
      /*类选择器*/
      .c1{color:yellow}
      /*分组选择器*/
      h4,#p1,.c1{background-color:blue }
      /*属性选择器*/
      input[type="text"]{color: red}
      /*任意元素选择器*/
      /*边框：粗细 样式 颜色*/
      *{border: 1px solid purple}
    </style>
</head>
<body>
<input type="text">
<input type="password">

<p id="p1">苹果</p>
<p class="c1">香蕉</p>
<p>橘子</p>
<h3>冰箱</h3>
<h3 class="c1">洗衣机</h3>
<h3>电视机</h3>
<h4>张三</h4>
</body>
</html>